I am opposed to nuclear weapons, and any other weapons of mass destruction. Unfortunately that cat is out of the bag. But many of the nations which have nuclear weapon capability have tried to prevent other countries from obtaining them. Currently that includes Iran.

What is the basis for denying Iran the right to develop and possess nuclear weapons?

“The place to improve the world is first in one's own heart and head and hands, and then work outward from there.” 
― Robert M. Pirsig, Zen and the Art of Motorcycle Maintenance: An Inquiry Into Values

What if the US and other countries with nuclear weapons decided to unilaterally disarm?